Almost six months ago we announced that Cataclysm raids were being redesigned to make both raid sizes the same difficulty, drop the same quality of loot, and exist in the same lockout. This evolution in raid philosophy is built on the belief that the size of your raiding group should be a choice based solely on what's more fun and enjoyable for you, and that you should not have to complete the same raiding content twice in a week to maximize your character's progression. These systems are the culmination of a great deal of design and player feedback from the last few years. With the release of the 4.0.1 patch, the new Flexible Raid Lock system will debut in Icecrown Citadel and The Ruby Sanctum.

With the Flexible Raid Lock system, instead of being locked to a specific raid size or raid group, each character will have the opportunity to defeat each raid encounter once a week. You could kill Lord Marrowgar and Lady Deathwhisper with a 10-player raid on Wednesday, join a 25-player raid to kill Festergut and Rotface on Thursday, and then lead a completely new 10-player raid to kill The Lich King on Friday. Every raid has a list of encounters associated with the zone. For example, Icecrown Citadel has twelve encounters. After you defeat Lord Marrowgar, you can open up your character's raid information dialog and see the list of encounters in Icecrown Citadel with Marrowgar marked as defeated. You may no longer fight Lord Marrowgar with any raid size or difficulty until the weekly raid reset for your region occurs.

Another key change is that if you join someone else's raid in progress, you are no longer locked to that raid after merely zoning in. Your raid status will only change when a boss is defeated, at which point it will be updated to reflect the state of the instance in which you are currently participating. So, let's say you have killed the first four bosses of Icecrown Citadel, and you then join a raid that has defeated the first four encounters, as well as Festergut and Rotface. The dialog that displays upon entering Icecrown Citadel will show that the raid has defeated 6 of 12 encounters. If you help them defeat Professor Putricide, then you would be marked as having defeated not only Professor Putricide for the week, but also Festergut and Rotface. If instead after joining the raid you then proceeded to wipe ten times to Professor Putricide, you could leave the raid with only the first four bosses marked as completed.

To help communicate to players which bosses are dead in the raid leader's raid, there is new functionality to link in chat a list of the encounters the raid has defeated. So before you join a raid, you can see what they've already defeated. If a raid leader advertises in chat that she needs another healer for an 8/12 Icecrown Citadel run, you can see precisely which bosses are still available to fight. If you were only looking for that one item from Queen Lana'thel that never drops for you and this raid already defeated her, you will know not to join that raid.

Let's look at another example of the Flexible Raid Lock system. A guild schedules three nights for 25-player Icecrown Citadel raiding on Wednesday, Thursday, and Saturday. On Wednesday, the raid defeats Lord Marrowgar, Lady Deathwhisper, Icecrown Gunship Battle, and Saurfang. On Thursday, five people cancel their raid attendance due to real life emergencies. The raid leader knows that if he cancels Thursday raiding, there's little chance they'll have enough time on Saturday to defeat the other eight bosses in Icecrown Citadel. So he splits the remaining 20 Thursday raiders into two 10-player raids. Each new raid enters Icecrown Citadel and defeats Rotface, Festergut, Blood Council, and Valithria Dreamwalker. The next Saturday with all 25 players online, they reform as a 25-player raid and enter Icecrown Citadel once more. Only Professor Putricide, Queen Lana'thel, Sindragosa, and The Lich King remain. After a tough fight, the Lich King falls and everybody celebrates. Without the Flexible Raid Lock system the entire raid probably would have missed out on a night of raiding, and likely would not have reached the Lich King.

While players can freely move between raids of different sizes in normal difficulty, there are some additional rules for Heroic difficulty. If a 10- or 25-player raid defeats a boss on Heroic difficulty, then those players may now only raid additional Heroic encounters with that specific raid. If your Heroic 25-player raid defeats the first four bosses of Icecrown Citadel on Heroic, then they may not split up into two 10-player raids and continue to fight in Heroic difficulty. You may also not join someone else's raid if they have defeated a Heroic encounter.

But let's say you are a member of a Heroic raid in Icecrown Citadel, and after killing Lord Marrowgar on Heroic you have Internet connection issues that prevent you from raiding for two nights. During those two nights, the rest of the raid kills everything. Without the Flexible Raid Lock system, you would be done with raiding Icecrown Citadel for the week. Ouch. With the Flexible Raid Lock system, you can join someone else's raid as long as they are doing Normal difficulty. This would at least give you the opportunity to earn your Justice Points for the week. If this raid attempted to switch to Heroic difficulty for Icecrown Gunship Battle with you in the raid, the raid leader would receive an error message stating that she cannot change to Heroic, because someone in the raid (i.e., you) is already locked to a different Heroic instance.

All of the new Cataclysm raids will feature the Flexible Raid Lock and Dynamic Difficulty systems, and when the Cataclysm occurs the other Wrath of the Lich King raids will also have these features. It's important to note that this system doesn't affect Heroic dungeons, they will work as they always have. We look forward to feedback for this new system after 4.0.1 is released. As a reminder, Icecrown Citadel and The Ruby Sanctum are the only two raids that support the Flexible Raid Lock until the Cataclysm occurs.

Update
One piece of clarification on questions being asked so far, although we're still compiling feedback and will work to answer some of the questions and clear up any confusion we can.

The loot system in Icecrown and Ruby Sanctum is not changing. This implementation of the new flex raid lock is only that, a new implementation of the raid lockout system we'll be using in Cataclysm. This does not change the separation of 10 and 25 in ICC, and does not change the item drops or achievements.

This is really awesome. About half of this wall of text includes examples given to help people understand, but I'm glad this has been touched on once more and clarified. I remember them mentioning the ability to do this, and was hoping the original specifics would get implemented. Yay!

I wish I worked at Bliz. The simple version of this would be "Each player can only loot each boss once per week regardless of raid size or difficulty." That is the solution I've been suggesting since day 1. This would allow people to raid with whatever friends they want, whenever they want. And never HAVE to raid more than once for the sake of min/maxing progression. They're half way there. Maybe someday they'll figure it out.

Nice, this might actually open up a few people who were opposed to pugging before. Even though my reason is because I like raiding with my friends, I can still see where some people might give pugging a chance. Blizz gets 2 interwebz for this.

Can't say I care for the heroic portion of it.. wish it was as flexible as the normal -> heroic -> normal swapping as we have currently for ICC. Will kill a lot of the flexibility of the new system for those guilds that are currently working on heroic content only since you won't be able to swap to a 10 man version of the instance.

I know it will retain the current flexibility, but just not the same flexibility that normal mode will enjoy in 4.0.1+